U.S. patent number 6,620,879 [Application Number 09/913,148] was granted by the patent office on 2003-09-16 for powdery polyether carboxylate-based polymeric compositions.
This patent grant is currently assigned to Degussa Construction Chemicals GmbH. Invention is credited to Gerhard Albrecht, Alfred Kern, Hubert Leitner, Josef Weichmann.
United States Patent |
6,620,879 |
Albrecht , et al. |
September 16, 2003 |
Powdery polyether carboxylate-based polymeric compositions
Abstract
A description is given of pulverulent polymer compositions based
on polyether carboxylates, which are characterized in that they
comprise a) from 5 to 95% by weight of a water-soluble polymer made
up of polyoxyalkylene-containing structural units, carboxylic acid
and/or carboxylic anhydride monomers and, if desired, further
monomers, and b) from 5 to 95% by weight of a finely divided
mineral support material having a specific surface area of from 0.5
to 500 m.sup.2 /g (determined by the BET method in accordance with
DIN 66 131). These pulverulent polymer compositions, which can
contain up to 90% by weight of polyether carboxylate, have a
significantly increased sticking and caking resistance compared to
spray-dried products and have further advantages when they are used
in cement-containing building material mixtures.
Inventors: |
Albrecht; Gerhard (Tacherting,
DE), Leitner; Hubert (Haus/Ennstal, AT),
Kern; Alfred (Kirchweidach, DE), Weichmann; Josef
(Pleiskirchen, DE) |
Assignee: |
Degussa Construction Chemicals
GmbH (Trostberg, DE)
|
Family
ID: |
7897031 |
Appl.
No.: |
09/913,148 |
Filed: |
September 24, 2001 |
PCT
Filed: |
February 08, 2000 |
PCT No.: |
PCT/EP00/00999 |
PCT
Pub. No.: |
WO00/47533 |
PCT
Pub. Date: |
August 17, 2000 |
Foreign Application Priority Data
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Feb 10, 1999 [DE] |
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199 05 488 |
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Current U.S.
Class: |
524/522; 521/106;
524/442; 524/492 |
Current CPC
Class: |
C04B
20/1033 (20130101); C04B 24/267 (20130101); C08G
65/3324 (20130101); C08K 3/01 (20180101); C08L
71/02 (20130101); C08K 3/013 (20180101); C04B
20/1033 (20130101); C04B 14/066 (20130101); C04B
20/008 (20130101); C08K 3/01 (20180101); C08L
71/02 (20130101); C08K 3/013 (20180101); C08L
71/02 (20130101); C08L 71/02 (20130101); C04B
2103/408 (20130101); C08L 2666/04 (20130101) |
Current International
Class: |
C08G
65/00 (20060101); C08K 3/00 (20060101); C08G
65/332 (20060101); C08L 71/02 (20060101); C08L
71/00 (20060101); C08J 003/00 () |
Field of
Search: |
;521/106
;524/522,442,492 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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43 25 483 |
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Feb 1995 |
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DE |
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0 838 444 |
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Apr 1998 |
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EP |
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0838444 |
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Apr 1998 |
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EP |
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2281074 |
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Feb 1995 |
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GB |
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07-118046 |
|
May 1995 |
|
JP |
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10-045451 |
|
Feb 1998 |
|
JP |
|
Other References
JP Patents Abstracts of Japan--63-39934 A., C-512, Jul. 15, 1998,
vol. 12, No. 252. .
2-99531 (A); C-734, Jun. 29, 1990, vol. 14, No. 304. .
2-153948 (A), C-754, Sep. 4, 1990, vol. 14, No. 406. .
Derwent Abst. Ref. 95-203649/27--Abst. JP 7118046 A..
|
Primary Examiner: Wu; David W.
Assistant Examiner: Hu; Henry S.
Attorney, Agent or Firm: Fulbright & Jaworski L.L.P.
Claims
What is claimed is:
1. A pulverulent polymer composition based on polyether
carboxylates, comprising a. from 5% to 95% by weight of a
water-soluble polymer made up of polyoxyalkylene-containing
structural units, carboxylic acid or carboxylic anhydride monomers;
and, b. from 5% to 95% by weight of a finely divided mineral
support material having a specific surface area of from 0.5 m.sup.2
/g to 500 m.sup.2 /g as determined by the BET method in accordance
with DIN 66 131 and is obtained by spraying molten polyether
carboxylate onto a mineral support material at a temperature of
from 70.degree. C. to 120.degree. C.
2. The polymer composition according to claim 1, wherein the
water-soluble polymer contains polyethylene glycol or
polypropoylene glycol groups in its main chain or in its side
chain.
3. The polymer composition according to claim 1, wherein the
carboxylic acid or carboxylic anhydride mononers comprise acrylic
acid, methacrylic acid, maleic acid, maleic acid anhydride, fumaric
acid, itaconic acid or itaconic anhydride.
4. The polymer composition according to claim 1, wherein the
water-soluble polymer further comprises monomers based on vinyl or
acrylate compounds.
5. The polymer composition according to claim 1, wherein the
support material is selected from the group consisting of chalk,
silica, calcite, dolomite, quartz flour, bentonite, ground pumice,
titanium dioxide, fly ash, cement, aluminum silicate, talc,
anhydrite, lime, mica, kieselguhr, gypsum, magnesite, alumina,
kaolin, ground slate and other rocks, barium sulfate, and mixtures
thereof.
6. The polymer composition according to claim 1, wherein the
mineral support materials are used in combination with at least one
organic additive.
7. The polymer composition according to claim 1, wherein the
support materials have a particle size of from 0.1 .mu.m to 1000
.mu.m.
8. A process for preparing the polymer composition according to
claim 1, comprising incorporating the polyether carboxylate into
the mineral support material immediately after the polymerization
of the polyether carboxylate.
9. The process according to claim 8, wherein the polyether
carboxylate is a bulk polymer.
10. The process according to claim 8, further comprising spraying
molten polyether carboxylate onto a preheated mineral support
material at a temperature of from 70.degree. C. to 120.degree.
C.
11. The process according to claim 8, wherein the polyether
carboxylate is incorporated into the mineral support material in
the form of an aqueous solution, an inverse emulsion or a
suspension.
12. The process according to claim 8, wherein said support material
has a porous structure, and said polyether carboxylate is
incorporated into said support material by using a mixer which
produces low shear forces.
13. A method for making a building material, comprising combining
from 0.1% to 5% by weight of the pulverulent polymer composition of
claim 1, with a pre-existing building material.
14. The method of claim 13, wherein said pre-existing building
material is a bitumen product, a building material based on
hydraulically setting binders, a gypsum based product, a calcium
sulfate based product, a ceramic composition, a refractory
composition, an oil field material, or a dispersion based
material.
15. The method of claim 13, further comprising adding at least one
of building material additive or a filler component.
16. The method of claim 14, wherein said additive is a dispersion
powder, a water retention improver, a thickener, a retardant, an
accelerator or a wetting agent.
17. The pulverulent polymer composition of claim 1, wherein said
water soluble polymer comprises an additional monomer.
18. The pulverulent polymer composition of claim 1, wherein said
additional monomer is a carboxylic acid monomer, or a carboxylic
anhydride monomer.
19. The polymer composition of claim 5, wherein said cement is
Portland cement or blast furnace cement.
20. The polymer composition of claim 6 wherein said at least one
organic additive is a cellulose powder, a cellulose fiber, an
organic polymer powder or an organic polymer fiber.
21. The process according to claim 12, wherein said mixer is a free
fall mixer.
22. The method of claim 14, wherein said hydraulically setting
binder is cement or a latent hydraulic binder.
23. The method of claim 14, wherein said calcium sulfate based
product is a calcium sulfate anhydrite.
Description
DESCRIPTION
The present invention relates to pulverulent polymer compositions
based on polyether carboxylates, processes for preparing them and
their use.
Water-soluble polymers comprising polyoxyalkylene-containing
structural units, carboxylic acid and/or carboxylic anhydride
monomers and, if desired, further monomers, hereinafter referred to
as polyether carboxylates, have recently found uses in a variety of
applications.
Apart from their use as dispersion stabilizer in the preparation of
water-soluble copolymers (WO 97/30 094), their use as protective
colloid in the production of caking-resistant dispersion powders
has been described. However, polyether carboxylates are preferably
used in building materials such as concrete, mortars, bitumen,
knifing fillers, adhesives, pigment-containing paints and coating
compositions, in ceramic compositions, in the refractories industry
and petroleum processing to exert a targeted influence on the
rheological and/or wetting properties of these building materials.
Adsorptive interactions which polyether carboxylates can undergo
with the hydraulic binder particles of these building materials
(cement, lime, calcium sulfate, etc.) result in stabilization of
the mineral particles combined with reduced internal friction and
thus in improved flow and processing properties. Although these
polymers consist of only two significant structural units, namely a
polyoxyalkylene-containing unit and a carboxylic acid(anhydride)
monomer, a large number of types of linkage are possible. The
structural variety of such polyether carboxylates extends from
random, alternating or block polymers through to comb polymers
having carboxyl groups in the main chain and polyether units in the
side chain. Also included are graft copolymers which are formed by
functionalization of polyethers by means of monomers containing
carboxylic acid groups.
Finally, the group of polyether carboxylates also includes
polyesters which are formed by reaction of polyethers, such as
polyethylene glycol, with polybasic carboxylic acids or carboxylic
anhydrides. It is immaterial whether these polymers are present as
the free acid or in their salt form.
The technical advantage of such products as fluidizers in
cement-based building materials is, firstly, that long-lasting
processability as desired by the concrete transport industry can be
achieved with use of extremely small amounts. Secondly, these
additives enable the proportion of water to be reduced so greatly
that it is possible to produce high-strength concrete which can be
removed from the mold or from which the shattering can be removed
after only 12 hours, thus meeting a central requirement of the
prefabricated parts industry. In addition, the polymers are free of
toxicologically problematical constituents such as formaldehyde,
which distinguishes them from conventional cement flow improvers,
e.g. as disclosed in EP-B 214 412 or DE-C 16 71 017. For a series
of applications, it is useful and desirable to provide the
water-soluble polyether carboxylates in the form of their aqueous
solutions.
However, the use of aqueous preparations can be completely ruled
out in other fields of application where the polymers are required
as additives in factory-produced dry mixes.
Apart from logistic and economic advantages (transport of water!),
powders have a number of technical advantages over aqueous
preparations. Stabilization against attack by microorganisms by
means of addition of biocides becomes unnecessary as do the
sometimes complicated measures for tank hygiene. Since polyether
carboxylates can, owing to their surface-active properties,
introduce undesirably high proportions of air into the building
material, antifoams are generally mixed into the aqueous
preparations after they have been prepared.
Owing to the incompatibility of the antifoam in the aqueous medium
of the polyether carboxylate, sedimentation and/or flotation
phenomena occur, which leads to considerable problems at the end
user.
If the polyether units in the polyether carboxylates are
incorporated in the main chain or bound as side chain constituents
on the main chain via ester groups, undesirable hydrolysis with
destruction of the polymer structure can occur already during
storage of the aqueous preparations.
This problem can be countered only "symptomatically" by storage at
low temperatures, which greatly restricts the use of such aqueous
preparations, particularly in hot climatic zones. In addition to
the unsatisfactory stability at temperatures above 30.degree. C.,
there is the sensitivity to frost. Owing to the abovementioned
facts, the use of powders has always been found to be preferable to
the use of aqueous preparations.
According to the prior art, polymer powders based on polyether
carboxylates are obtained by spray drying the aqueous preparations
in a stream of hot air, during which antioxidants and spray-drying
auxiliaries are advantageously added so as to a) prevent
spontaneous heating or spontaneous ignition of such polymers during
and after the drying process and b) inhibit adhesion of the
wax-like polymer particles in the dryer.
Neglect of the safety risks mentioned under a) has in the past led
to fires during the spray drying process. Furthermore, despite the
use of spray-drying auxiliaries, it is sometimes difficult to
isolate a non-sticky and caking-resistant polymer powder,
especially when the proportion of polyether in the polymer is high
and the proportion of carboxyl groups is low. These disadvantages,
the high energy requirement for spray drying and the emission
limits to be adhered to during spray drying are particularly
serious.
The procedure in which the polyether carboxylate is firstly
produced in a solvent-free polymerization, diluted with water and
subsequently neutralized is particularly uneconomical. After that,
spray drying is carried out with the abovementioned disadvantages
in order to remove the water introduced in the dilution
process.
It is therefore an object of the present invention to provide
pulverulent polymer compositions based on polyether carboxylates
which avoid the disadvantages of the prior art, i.e. give products
which are storage-stable at high temperatures and are also
insensitive to frost, require no preservatives, are stable to
spontaneous ignition and thermal oxidative degradation, give
sticking- and caking-resistant powders and are obtainable at a low
energy consumption and by a rational process.
According to the invention, this object is achieved by pulverulent
polymer compositions comprising a) from 5 to 95% by weight of a
water-soluble polymer made up of polyoxyalkylene-containing
structural units, carboxylic acid and/or carboxylic anhydride
monomers and, if desired, further monomers, and b) from 5 to 95% by
weight of a finely divided mineral support material having a
specific surface area of from 0.5 to 500 m.sup.2 /g (determined by
the BET method in accordance with DIN 66 131).
It has surprisingly been found that the incorporation of the
polyether carboxylates (component a) into the mineral component b)
can be made so effectively that up to 90% by weight of active
ingredient, i.e. the polyether carboxylate component, in the
polymer composition can be achieved.
In addition, it was particularly surprising that the sticking and
caking resistance was considerably increased compared to
spray-dried products and additional advantages were found in the
use of the compositions in cement-containing building material
mixtures.
The water-soluble polymers used for preparing the polymer
composition of the invention are products which contain
polyoxyalkylene groups, preferably polyethylene glycol or
polypropylene glycol groups, in the main chain or in the side chain
and additionally comprise carboxylic acid and/or carboxylic
anhydride monomers, preferably acrylic acid, methacrylic acid,
maleic acid, maleic anhydride, fumaric acid, itaconic acid and
itaconic anhydride. Further monomers based on vinyl or acrylate
groups can additionally contribute to making up the polyether
carboxylates. Examples of such further monomers are styrene,
.alpha.-methylstyrene, isobutene, diisobutene, cyclopentadiene,
ethylene, propylene, isoprene, butadiene, acrylonitrile,
chloroprene, vinyl acetate, N-vinylpyrrolidone, methyl acrylate,
methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate,
acrylamide, methacrylamide, acrylamidomethylpropane-sulfonic acid,
styrenesulfonic acid, vinyl chloride, methyl vinyl ether, ethyl
vinyl ether, allyl alcohol, allylsulfonic acid, allyl chloride and
others.
The polymers can be linear, have short-chain branching, have
long-chain branching or be crosslinked and can have comb
structures, star structures, dumb-bell structures and other
morphologically conceivable structures.
Examples are block copolymers of polymethacrylic acid and
polyethylene glycol, comb-like polymers having a polymethacrylic
acid main chain and individual polyethylene oxide side chains bound
via ester groups, maleic anhydride/styrene copolymers partially
esterified with methylpolyethylene glycol, allylpolyethylene
glycol/maleic acid copolymers, vinylpolyethylene glycol/maleic
monoester copolymers, graft copolymers comprising a polyethylene
glycol or polypropylene glycol skeleton and maleic anhydride or
acrylic acid side chains which may in turn be esterified or
partially esterified.
Polyesters, polyamides and polyurethanes which are based on
alkylene oxides such as ethylene oxide, propylene oxide or butylene
oxide and bear ionic groups and are therefore water-soluble are
also possible.
These polyether carboxylates can be in the form of their free acids
or in neutralized form and can be prepared by solution
polymerization, bulk polymerization, inverse emulsion
polymerization or suspension polymerization.
In preferred embodiments, polyether carboxylates prepared by bulk
polymerization are used. In the case of these, the usefulness of
the invention is particularly high since in the prior art these
firstly have to be diluted with water, neutralized and subsequently
subjected to spray drying to remove the previously introduced water
and convert them into a powder.
It is an essential aspect of the invention that the finely divided
mineral support materials used have a specific surface area of from
0.5 to 500 m.sup.2 /g (determined by the BET method in accordance
with DIN 66 131). The proportions by weight of support materials in
the pulverulent polymer compositions depend on the type of polymer,
its composition and the form in which it is incorporated and also
on the specific surface area and the adsorption capacity of the
mineral support material. They can therefore vary within a very
wide range from 5 to 95% by weight.
The type of these support materials is subject to no particular
restriction. It is important that the material is readily
compatible with the polyether carboxylate, does not have an adverse
effect on the action of the polymer and even in small amounts gives
pulverulent sticking- and caking-resistant polymer
compositions.
Preference is given to using chalk, silica, calcite, dolomite,
quartz flour, bentonite, ground pumice, titanium dioxide, fly ash,
cement (Portland cement, blast furnace cement, etc.), aluminum
silicate, talc, anhydrite, lime, mica, kieselguhr, gypsum,
magnesite, alumina, kaolin, ground slate and other rocks, barium
sulfate and also mixtures of these materials. According to a
preferred embodiment, the mineral support material already
comprises one or more mineral components of a building
material.
The finely divided support materials have a preferred particle size
of from 0.1 to 1000 .mu.m.
If desired, the mineral support materials can be used in
combination with organic (nonmineral) additives such as cellulose
powders or cellulose fibers and also powders or fibers of organic
polymers (polyacrylonitrile, polystyrene, etc.).
The invention also provides a process for preparing the pulverulent
polymer compositions, which is characterized in that the polyether
carboxylate is incorporated into the respective mineral support
material immediately after the polymerization process for preparing
the polyether carboxylate. The polymer is preferably introduced
into the initially charged and, if desired, preheated mineral
support material in as finely divided a form as possible, with the
polyether carboxylate being a bulk polymer or being able to be in
the form of an aqueous solution, an inverse emulsion or a
suspension.
In a preferred embodiment, a polyether carboxylate prepared by bulk
polymerization at from 110 to 140.degree. C. is sprayed at a
temperature in the range from 70 to 120.degree. C. onto a preheated
mineral support material (for example of the silica type) in a
mixer.
Particularly effective incorporation with very low consumption of
mineral support material can be achieved by applying the polyether
carboxylate as a mist onto the preheated support material. The
effectiveness drops when the polymer is sprayed, dripped or poured
onto the support material, because the surface area of the
substance to be incorporated decreases in that order.
Furthermore, the mixing technique in the incorporation is of
particular interest and depends very strongly on the type of
support material used.
Support materials having a pronounced porous structure, e.g.
silicas, have a particularly high adsorption capacity.
Mixers in which high shear forces occur near the mixing devices can
destroy the porous structure, as a result of which polyether
carboxylates present in the voids can be squeezed out again. It is
therefore advisable to use mixing apparatuses in which low shear
forces occur, e.g. drum mixers, V mixers, tumble mixers or other
representatives of free-fall mixers, for this type of support.
Further suitable mixers for porous supports are cone mixers,
plowshare mixers or spiral mixers having vertically or horizontally
installed mixing elements. In the case of mineral supports whose
structure cannot be destroyed by the mixing process, all other
types of apparatus, e.g. dissolvers, screw mixers, twin-screw
mixers, air-mix mixers and others, are also usable.
Finally, it is possible within the scope of the present invention
to follow the incorporation of the polyether carboxylate into the
support by a drying process so as to increase the productivity of
the support material.
The invention further provides for the use of at least one
pulverulent polymer composition according to the present invention
in building materials, suitable building materials being bitumen
products, such as asphalt, bituminous adhesive, sealing, knifing
and paint or coating compositions (rooftop parking areas), or
products based on hydraulically setting binders such as cement or
based on latent hydraulic binders such as fly ash and trass, such
as mortar (casting mortar), screeds, concrete, plasters and
renders, adhesive, sealing and knifing compositions and also
paints. A further group of possible building materials comprises
gypsum-based building materials (mortar, plaster, screed),
anhydrite-based building materials, the other building materials
based on calcium sulfate, the group of ceramic compositions,
refractory compositions and oilfield materials. Finally, the
polymer compositions of the invention can also be used in
dispersion-based building materials such as dispersion tile
adhesives, elastic sealing slurries, foundation coatings, mortar
adhesion additives and pulverulent interior and exterior wall
paints.
The pulverulent polymer compositions of the invention can also be
used in combination with the abovementioned groups of building
materials, e.g. in bitumen-containing cement screeds, casting
mortars, etc.
The incorporation of the pulverulent polyether carboxylates into
the building material is generally carried out together with that
of other fillers and building material additives, such as
dispersion powders, water retention improvers, thickeners,
retardants, accelerators, wetting agents, etc. The proportion of
polyether carboxylate is usually from 0.1 to 5% by weight, based on
the weight of the building material. The pulverulent polymer
compositions of the invention have a series of advantages compared
to polyether carboxylates obtained in powder form by conventional
means. This will be illustrated by the following examples.
EXAMPLES
Example 1
In a tumble mixer from Bachofen AG, Basle, a pulverulent polymer
composition consisting of 75 g of a precipitated silica having a
specific surface area of 190 m.sup.2 /g and preheated to 80.degree.
C. and 425 g of a molten polyether carboxylate (A) is prepared at
80.degree. C. by mixing for 75 minutes.
The polyether carboxylate (A) was prepared by solvent-free
polymerization as follows:
50.1 g of maleic anhydride (0.51 mol) are esterified with 294 g of
methylpolyethylene glycol 1150 (0.256 mol) at a temperature of
120.degree. C. for 3 hours with careful exclusion of atmospheric
oxygen. 72.8 g of styrene (0.7 mol) containing a small amount of
n-dodecyl mercaptan and 8.3 g of azobisisobutyronitrile dissolved
in 50 ml of acetone were introduced as separate feed streams at
110.degree. C. over periods of 90 min and 120 min respectively into
the initial mixture obtained in this way. The reaction vessel was
continually flushed with nitrogen so that much of the acetone could
be driven out even during the feed stream addition phase. In a
2-hour after-reaction at 120.degree. C., the remaining acetone was
removed to give a light-yellow bulk polymer of maleic anhydride,
styrene and methylpolyethylene glycol 1150 monomaleate in a molar
ratio of 0.5:1.37:0.5 (polyether carboxylate A). After addition of
0.5% by weight of an antioxidant and spraying onto the
abovementioned mineral support material and mixing for 75 minutes,
a sticking- and caking-resistant, free-flowing, ivory-colored
powder having an active content of polyether carboxylate of 85
percent by weight (mean particle diameter: 39 .mu.m) was
obtained.
Comparative Example 1
In accordance with the prior art, the bulk polymer synthesized in
Example 1 was cooled to 80.degree. C. and stirred into 425 g of
water. After the aqueous solution obtained had cooled, the pH was
set to 8.5 by slow addition of dilute aqueous sodium hydroxide.
0.5% by weight, based on the polymer content, of an antioxidant was
stirred in, and the polymer solution was, for viscosity reasons,
diluted with water to 30% by weight before being converted into a
powder in a laboratory spray dryer from NIRO. This gave a
light-brown powder which had a mean particle diameter of 54 mm
[sic] and had a very strong tendency to form lumps.
The powders obtained in the examples were characterized in respect
of the following data: 1. Polymer content (GPC) 2. Flow behavior of
the powders (outflow from a vessel with a bottom outlet) 3. Caking
resistance of the powders (under 2 kg pressure) 4. Fluidizing
effect in a cement building material mixture
Examples 2 to 9
These were carried out using the procedure described in Example 1,
but the following finely divided mineral support materials were
used in place of the silica used there (Table 1):
TABLE 1 Proportion Support by weight Specific of surface Polymer/
area Support Example Type (m.sup.2 /g) (%) 2 chalk 11 40:70 3
dolomite (micronized) 4 45:55 4 kieselguhr 65 55:45 5 calcium
silicate 35 70:30 6 aluminum silicate 100 50:50 7 sodium aluminum
silicate 80 65:35 8 precipitated silica 450 80:20 9 precipitated
450 75:25 silica/chalk (1:1) 11
Examples 10 to 15
In place of the polyether carboxylate obtained by solvent-free
copolymerization which was used in Example 1, the following
polymers were used (Table 2):
TABLE 2 Weight ratio of polymer/ Ex- Polyether support.sup.1) ample
carboxylate.sup.2) Type of synthesis (%) 10 B bulk polymerization
87:13 11 C bulk polymerization 90:10 12 D bulk polymerization 81:19
13 E bulk polymerization 80:20 14 F bulk polymerization 75:25
(graft polymerization) 15 G aqueous solution 67:33 polymerization
.sup.1) Support: precipitated silica (specific surface area: 190
m.sup.2 /g) .sup.2) Polymer compositions: B Maleic
anhydride-styrene-methylpolyethylene glycol 2000 monomaleate
copolymer (molar ratio = 0.60:1.37:0.40) C Maleic
anhydride-styrene-methylpolyethylene glycol 5000 monomaleate
copolymer (molar ratio = 0.73:1.37:0.27) D Maleic
anhydride-allylpolyethylene glycol 1100 monoethyl ether copolymer
(molar ratio = 1.15:1) E Maleic anhydride-vinylpolyethylene glycol
500 monomethyl ether copolymer (molar ratio = 1.10:1) F to 50 mol
%-esterified graft copolymer of methylpolyethylene glycol 500 and
maleic anhydride (molar ratio = 1:1.6) G Maleic acid-ethylene
glycol monovinyl ether-methylpolyethylene glycol 2000 monoethyl
ether copolymer (molar ratio = 0.40:0.85:0.37), solids content =
45%, sodium salt, pH = 6.5)
Comparative Examples 2 to 7
The polyether carboxylates B to G listed in Examples 10 to 15 were
diluted, neutralized, provided with an antioxidant and converted
into powder by means of spray drying using the procedure indicated
in Comparative example 1.
The test results obtained from Examples according to the invention
1 to 15 and Comparative examples 1 to 7 are summarized in the
following use examples.
Use Example 1
Polymer Content of the Pulverulent Polymer Compositions in the
Examples According to the Invention and the Comparative
Examples
The polymer content was determined by gel permeation chromatography
(conditions: Waters (Milford, Mass.); Shodex OH Pak KB-804 and
KB-802.5; standard: polyethylene glycol; eluant: NH.sub.4.sup.+
HCOO/CH.sub.3 CN 80:20 v/v).
It has been found that direct conversion of the polymers as
described in Examples 1 to 15 into powders is not associated with a
reduction in the active polymer content. In contrast, in the case
of polymers which contain ester bonds and have been converted into
powders by methods according to the prior art, the polymer content
after spray drying is significantly reduced. This is attributable
to part of the polyether constituents bound via ester groups in the
polyether carboxylates in the form of comb or graft copolymers
being split off in the dilution, neutralization and spray drying
process.
TABLE 3 Polymer content.sup.2) (% by weight) Polyether after in the
Example carboxylate.sup.1) polymerization powder Example 1 A 89.7
89.6 Example 2 A 88.9 88.7 Example 6 A 87.4 87.6 Example 8 A 86.6
86.7 Example 9 A 88.0 88.0 Comparison 1 A 89.2 79.4 Example 10 B
82.2 83.0 Comparison 2 B 81.7 73.6 Example 11 C 79.5 79.5
Comparison 3 C 79.2 70.0 Example 14 F 90.4 90.3 Comparison 6 F 90.3
83.8 .sup.1) Polymer composition as per Example 1 and Table 2
.sup.2) GPC
Use Example 2
Powder Flow Behavior of the Polymer Compositions According to the
Invention and of Comparative Polymers
The powder flow (without application of pressure) was determined by
the method of K. Klein: Seifen, Ole, Fette, Wachse 94 (1968), page
12, for various polymer compositions. For this purpose,
silicone-treated glass vessels with a bottom outlet and different
outlet diameters were filled to the brim with the test substance.
For the evaluation, grades were assigned on the scale from 1, i.e.
the powder flowed from the vessel with the smallest outlet opening
(.o slashed.=2.5 mm) without stopping, to 6, i.e. the powder does
not flow even from the vessel with the largest opening (.o
slashed.=18 mm). The measurements for each powder were commenced
using the vessel with the largest outlet opening.
TABLE 4 Powder flow Polyether Evaluation grade for Example
carboxylate.sup.1) powder flow Example 1 A very good (1) Example 2
A good-satisfactory (2-3) Example 3 A satisfactory (3) Example 4 A
good (2) Example 5 A good (2) Example 6 A good (2) Example 7 A very
good (1) Example 8 A very good (1) Example 9 A good (2) Comparison
1 A unsatisfactory (6) Example 10 B very good (1) Comparison 2 B
poor (5) Example 11 C very good (1) Comparison 3 C sufficient (4)
Example 12 D good (2) Comparison 4 D unsatisfactory (6) Example 13
E satisfactory (3) Comparison 5 E unsatisfactory (6) Example 14 F
good (2) Comparison 6 F sufficient (4) Example 15 G satisfactory
(3) Comparison 7 G sufficient (4) .sup.1) polymer composition as
per Example 1 and Table 2
Use Example 3
Caking Resistance of Polymer Compositions According to the
Invention and of Comparative Polymers
Pulverulent products tend to cake when stacked in bags or in a
hopper. To assess the caking resistance or "stackability", the
powder to be tested was introduced to a height of about 20 mm into
a steel cylinder having an internal diameter of 50 mm and loaded by
means of a punch having a weight of 1.2 kg and a loading weight of
2 kg.
The pressure prevailing in this test arrangement is 0.17
kg/cm.sup.2, which corresponds to the pressure of from 10 to 12
bags having a weight of 50 kg stacked on top of one another. After
loading for 24 hours, the loading weight was removed and the powder
pellet was ejected from the cylinder. The hardness of the powder
pellet is regarded as a criterion for the caking resistance
according to the following assessment scheme.
TABLE 5 Assessment Grade Behavioral feature very good 1 completely
unchanged good 2 adheres slightly, disintegrates into the original
state satisfactory 3 loosely shaped, disintegrates into a powder
under gentle finger pressure sufficient 4 loosely caked, just still
disintegrates poor 5 semifirmly caked, no longer disintegrates
unsatisfactory 6 strongly compacted
The following results were obtained:
TABLE 6 Polyether Evaluation code for Example carboxylate.sup.1)
caking resistance 1 A good (2) comparison 1 A sufficient (4) 10 B
good (2) comparison 2 B poor (5) 11 C good (2) comparison 3 C
satisfactory (3) 12 D good (2) comparison 4 D sufficient (4) 13 F
good (2) comparison 5 F sufficient (4) 15 G good (2) comparison 7 G
satisfactory (3) .sup.1) Polymer composition as per Example 1 and
Table 2
Use Example 4
Fluidizing Effect in a Cement-containing Building Material
The powder obtained from the examples according to the invention
and from the comparative examples were examined in respect of their
use properties in a mortar formulation. For this purpose, the
pulverulent polymer compositions were mixed dry with the amounts of
sand and Portland cement (CEM I 42.5 R Kiefersfelden) prescribed in
accordance with DIN 1164 part 7. This was followed by addition of
water and mixing of the constituents in accordance with the
standard. The slump of the fresh mortar was determined for each
powder type immediately and after 15, 30, 45 and 60 minutes
TABLE 7 Polymer Polyether Slump (cm) Example addition.sup.1)
carboxylate immediately 15 min 30 min 45 min 60 min 1 0.15 A 23.5
22.5 20.1 19.0 18.3 comparison 1 0.15 A 22.9 19.6 17.4 16.3 15.4 10
0.15 B 25.0 24.1 22.1 19.3 17.2 comparison 2 0.15 B 24.3 22.0 19.4
17.0 14.0 11 0.20 C 26.1 23.6 21.1 19.9 18.4 comparison 3 0.20 C
25.4 21.6 19.9 17.3 14.6 15 0.15 G 27.9 26.1 24.9 23.9 23.0
comparison 7 0.15 G 26.0 24.0 21.4 20.0 17.3 .sup.1) In % by weight
of polyether carboxylate based on the weight of cement .sup.2)
Polymer composition as per Example 1 and Table 2 W/Z=0.45 CEM I
42.5 R Kiefersfelden 1% by weight of tributyl phosphate based on
polymer
Due to the loss of polyether side chains, the processability of
mortar mixtures containing polymer powders prepared according to
the prior art deteriorates significantly more quickly than that of
mixtures containing pulverulent powder compositions according to
the invention. This is attributable to the reduced steric
stabilization of the cement particles.
* * * * *